Plasma reactor with minimal D.C. coils for cusp, solenoid and mirror fields for plasma uniformity and device damage reduction
First Claim
1. A method of processing a wafer in a plasma reactor comprising a workpiece support surface and an overhead source power applicator overlying a ceiling of the reactor and facing said workpiece support surface, comprising:
- generating a plasma in a process region over said workpiece support surface while supporting the workpiece on said workpiece support surface;
generating a DC magnetic field in said process region by applying respective DC current levels to concentric inner and outer DC coils above and displaced by different distances from said RF source power applicator and to a bottom DC coil at an axial location below said wafer;
determining an uncorrected plasma ion density distribution at said workpiece support surface;
determining changes in plasma ion density distribution as functions of D.C. current applied one at a time to respective ones of said inner, outer and bottom electromagnets;
mathematically adding said functions with said uncorrected plasma distribution for different combinations of D.C. currents applied to said inner, outer and bottom electromagnets, so as to compute plural trial plasma ion density distributions;
searching said trial plasma ion density distributions for at least one corresponding to a desired correction in plasma ion density distribution, and determining a corrective set of currents corresponding to coil currents associated with the one trial density distribution; and
performing the desired correction by applying said corrective set of currents to respective ones of said inner, outer and bottom electromagnets.
1 Assignment
0 Petitions
Accused Products
Abstract
A plasma reactor for processing a workpiece, includes a vacuum chamber defined by a sidewall and ceiling, and a workpiece support pedestal having a workpiece support surface in the chamber and facing the ceiling and including a cathode electrode. An RF power generator is coupled to the cathode electrode. Plasma distribution is controlled by an external annular inner electromagnet in a first plane overlying the workpiece support surface, an external annular outer electromagnet in a second plane overlying the workpiece support surface and having a greater diameter than the inner electromagnet, and an external annular bottom electromagnet in a third plane underlying the workpiece support surface. D.C. current supplies are connected to respective ones of the inner, outer and bottom electromagnets.
273 Citations
10 Claims
-
1. A method of processing a wafer in a plasma reactor comprising a workpiece support surface and an overhead source power applicator overlying a ceiling of the reactor and facing said workpiece support surface, comprising:
-
generating a plasma in a process region over said workpiece support surface while supporting the workpiece on said workpiece support surface; generating a DC magnetic field in said process region by applying respective DC current levels to concentric inner and outer DC coils above and displaced by different distances from said RF source power applicator and to a bottom DC coil at an axial location below said wafer; determining an uncorrected plasma ion density distribution at said workpiece support surface; determining changes in plasma ion density distribution as functions of D.C. current applied one at a time to respective ones of said inner, outer and bottom electromagnets; mathematically adding said functions with said uncorrected plasma distribution for different combinations of D.C. currents applied to said inner, outer and bottom electromagnets, so as to compute plural trial plasma ion density distributions; searching said trial plasma ion density distributions for at least one corresponding to a desired correction in plasma ion density distribution, and determining a corrective set of currents corresponding to coil currents associated with the one trial density distribution; and performing the desired correction by applying said corrective set of currents to respective ones of said inner, outer and bottom electromagnets. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A method of processing a wafer in a plasma reactor comprising a workpiece support surface and an overhead source power applicator overlying a ceiling of the reactor and facing said workpiece support surface, comprising:
-
generating a plasma in a process region over said workpiece support surface while supporting the workpiece on said workpiece support surface; generating a DC magnetic field in said process region by applying respective DC current levels to concentric inner and outer DC coils above and displaced by different distances from said RF source power applicator; determining an uncorrected plasma ion density distribution at said workpiece support surface; determining changes in plasma ion density distribution as functions of D.C. current applied one at a time to respective ones,of said inner and outer electromagnets; mathematically adding said functions with said uncorrected plasma distribution for different combinations of D.C. currents applied to said inner and outer electromagnets, so as to compute plural trial plasma ion density distributions; searching said trial plasma ion density distributions for at least one corresponding to a desired correction in plasma ion density distribution, and determining a corrective set of currents corresponding to coil currents associated with the one trial density distribution; and performing the desired correction by applying said corrective set of currents to respective ones of said inner and outer electromagnets. - View Dependent Claims (9, 10)
-
Specification